This invention relates to a mixed-phase cleaning solution and method for removing bacteria with pathogenic potential and other microorganisms, debris, tissue, food particles and the like from lines and tubing, and to an apparatus that delivers the mixed-phase cleaning solution under pressure to the lines and tubing to be cleaned.
Small bore tubing that delivers ordinary running water, purified or not, to fixtures such as dental units, develop bacterial and fungal growth from the water on their interior surfaces, as is well known. Bacteria present in the water strongly adhere to tubing surfaces and then grow laterally, forming what is known as biofilm. Biofilm is apparent to the touch as a slimy film which has been analyzed and found to be bacterial growth.
Several prior art workers have identified various bacteria included in these biofilms, which include several bacteria having pathogenic potential, such as Flavobacterium, Moraxella, Achromobacter, Pseudomonas, Alcaligenes, Micrococcus and Legionella. All of these bacteria have the potential to cause infections in humans, and legionella, which is highly resistant to antibiotics, is of particular concern since infection can be fatal. Organisms such as legionella can also be inhaled from contaminated water spray during dental or other medical treatment.
Dental unit tubing that carries rinse water to the mouth of patients has been determined to contain over one million (1xc3x97106) colony forming units of bacteria per milliliter of water (CFU/ml) after one week of use. Thus these water lines and tubing must be periodically cleaned to ensure the removal of this biofilm on the walls of the tubing to prevent infection. The potential for infection of immuno compromised patients is also a major concern. If the patient has any open wounds in the mouth, the danger of infection is of course much higher.
Biofilms are very difficult to remove from tubing however. The biofilm is strongly adherent to smooth tubing surfaces, whether the tubing is made from natural or synthetic materials such as rubber-based materials, polyethylene, polytetrafluoroethylene and the like. Treatment with disinfectant and biocidal agents may kill the bacteria and so remove the biofilm. However, these agents do not readily diffuse into the biofilm which strongly adheres to the tubing walls, and thus removal is generally only partial and the biofilm returns quite rapidly. Reduction of the level of bacteria present in water delivery systems to below 200 CFU/ml has been suggested by the American Dental Association.
Other applications employing small bore tubing that must be periodically cleaned include internal endoscopy tubing, catheter tubing, sterile filling ports, and tubing used for sterile manufacturing, food processing and the like. These types of tubing may contain, in addition to biofilm, food particles, tissue particles, mucous, blood and the like, which is referred to hereinafter as xe2x80x9cdebrisxe2x80x9d. Such tubing also must be thoroughly cleaned, these between each and every use, to prevent infection from one patient to another.
Guidelines for cleaning gastrointestinal endoscopy units promulgated by the American Society for Gastrointestinal Endoscopy include a multi-step method for cleaning tubing between patients to prevent infection. First, mechanical cleaning with a brush is performed, using a detergent solution, soon after use. The tubing is then rinsed with water and then a sterilization is carried out using a disinfecting solution such as a gluteraldehyde solution. The tubing is then rinsed with water again and then dried with forced air.
Other applications for the present invention are respirators, both neonatal and adult, which must be cleaned about every 8 hours or so. Such cleaning is expensive, but necessary.
Thus an improved cleaning composition and method for removing biofilm and debris from interior and external tubing surfaces in a cost effective manner and for preventing or delaying biofilm reoccurrence, and an apparatus to deliver these cleaning solutions to the lines and tubing that have become contaminated, would be highly desirable.
In accordance with the present invention, a combination of pressurized gas and a suitable aqueous cleaning solution is used to create a turbulent environment on or in a tubing having a biofilm or debris on interior or exterior surfaces, that completely removes the biofilm and debris. A suitable aqueous cleaning solution comprises water and a surfactant. An oxidizing agent and a biocidal agent can also be added. Inert particles that can provide a scrubbing action can also be added advantageously to the aqueous cleaning solution. This aqueous cleaning composition is delivered to the tubing to be cleaned by means of compressed gas, thus making a mixed-phase system, that provides a turbulent flow along the walls of the tubing that aids in loosening the biofilm and debris from the surfaces of the tubing, and aids in flushing the loosened materials from the tubing.
The invention also includes an apparatus for delivering the above mixed-phase cleaning solution to the interior of small bore tubing and lines and combining it with a gas under pressure. The compressed gas-aqueous cleaning solution combination develops turbulent flow inside the tubing that aids in loosening the biofilm from the interior surfaces of tubing so that it can be readily removed by flushing and rinsing with water.
The invention also includes an apparatus for delivering the above cleaning solution to the exterior surfaces of small bore tubing and lines, by encapsulating the tubing in a pressure-resistant sleeve having an adaptor that provides a pressure-tight seal between the cleaning solution-pressurized gas mixture and the tubing. The apparatus includes a mixing chamber for mixing the aqueous solution, optional solid particles and a gas under pressure for delivery to the lines and tubing to be cleaned.